So, by the news post on when the basic colors were released:

I had created one (Splintered*) and the zapper changed it into a Terracoon yet it stayed genderless.

Do they actually change from genderless when you use an elixir or zap them? I looked back through the news comments yet no one asked about this.

*There's a good chance that my pet may gain a gender after posting this as I'm still zapping it.

After reading this post, I went to check one of my pets, and noticed the same thing (lol I actually didn't read the news, and had no idea about the gender change)! The pet was created as a scootle originally, and later I decided to zap and also used a few experimental dews on them. They stayed genderless after all the species changes. Feel free to correct this and change the gender if needed.

Thank you. :) I was totally confused over them. I'll keep an eye if/whenever I make a new Scootle and end up changing it. Splintered isn't going to be changed anymore by me as I got a nice zap color.